1 files changed, 57 insertions, 0 deletions
diff --git a/src/loader/serial.c b/src/loader/serial.c
new file mode 100644
index 0000000..20299c4
--- /dev/null
+++ b/src/loader/serial.c
@@ -0,0 +1,57 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <cpu.h>
+#include <log.h>
+#include <panic.h>
+
+#define PORT 0x3f8
+
+void serial_install(void)
+{
+	outb(PORT + 1, 0x00);
+	outb(PORT + 3, 0x80);
+	outb(PORT + 0, 0x03);
+	outb(PORT + 1, 0x00);
+	outb(PORT + 3, 0x03);
+	outb(PORT + 2, 0xc7);
+
+	// Test serial chip
+	outb(PORT + 4, 0x1e); // Enable loopback
+	outb(PORT + 0, 0xae); // Write
+	assert(inb(PORT + 0) == 0xae); // Verify receive
+
+	// Activate
+	outb(PORT + 4, 0x0f);
+
+	log("[LOG] Initiated\n");
+}
+
+static int serial_empty(void)
+{
+	return inb(PORT + 5) & 0x20;
+}
+
+static void serial_put(char ch)
+{
+	while (serial_empty() == 0)
+		;
+	outb(PORT, (u8)ch);
+}
+
+void serial_print(const char *data)
+{
+	for (const char *p = data; *p; p++)
+		serial_put(*p);
+}
+
+void log(const char *format, ...)
+{
+	char buf[1024] = { 0 };
+
+	va_list ap;
+	va_start(ap, format);
+	vsnprintf(buf, sizeof(buf), format, ap);
+	va_end(ap);
+
+	serial_print(buf);
+}